Please refer to FIG. 1, normally for high efficiency DC/DC application, a Schottky rectifier is externally added in parallel with a MOSFET device to prevent a parasitic P/N body diode in the MOSFET from turning on in order to achieve higher speed and efficiency. The requirement for clamping effect is that the forward voltage of the Schottky rectifier Vf is less than the parasitic P/N body diode (˜0.7V). Besides, for providing effective ESD (electrostatic discharge) protection between gate (G, as illustrated in FIG. 1) and source (S, as illustrated in FIG. 1) and between gate and drain (D, as illustrated in FIG. 1), plurality poly-silicon Zener diodes are respectively implemented therein with breakdown voltage lower than that of the MOSFET device for clamping voltage between gate and source, and between gate and drain for avalanche protection. However, assembly of those separate structures into single package with extra interconnection wires results in higher manufacturing cost, and poor performance due to increase in inductance from the extra interconnection wires.
Accordingly, it would be desirable to provide more integrated MOSFET device with embedded Schottky rectifier diode, Gate-Drain and Gate-Source clamp diodes on single chip for device shrinkage and performance improvement.